U.S. patent number 6,171,438 [Application Number 09/227,332] was granted by the patent office on 2001-01-09 for plasma processing apparatus and plasma processing method.
This patent grant is currently assigned to Hitachi, Ltd.. Invention is credited to Tetsunori Kaji, Saburo Kanai, Toshio Masuda, Mitsuru Suehiro, Kazue Takahashi.
United States Patent |
6,171,438 |
Masuda , et al. |
January 9, 2001 |
Plasma processing apparatus and plasma processing method
Abstract
A plasma etching apparatus including a vacuum processing
chamber, a plasma generation device, a processing gas supply for
supplying processing gas to the processing chamber, an electrode
for holding a sample to be processed in the vacuum processing
chamber, and an evacuation system for reducing the pressure of the
vacuum processing chamber. The processing gas includes at least one
kind of gas having a composition for forming a polymerized film by
plasma discharge, wherein the processing gas is made plasmatic by
plasma discharge in the processing chamber. At least one surface of
an inner wall surface of the processing chamber in contact with
plasma in the processing chamber and a surface of an internal
component part is controlled to a predetermined temperature which
is lower than the temperature of the sample to be processed and a
strong polymerized film is formed on the inner wall surface of the
processing chamber.
Inventors: |
Masuda; Toshio (Toride,
JP), Takahashi; Kazue (Kudamatsu, JP),
Suehiro; Mitsuru (Kudamatsu, JP), Kaji; Tetsunori
(Tokuyama, JP), Kanai; Saburo (Hikari,
JP) |
Assignee: |
Hitachi, Ltd. (Tokyo,
JP)
|
Family
ID: |
13056650 |
Appl.
No.: |
09/227,332 |
Filed: |
January 8, 1999 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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611758 |
Mar 8, 1996 |
5874012 |
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Foreign Application Priority Data
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Mar 16, 1995 [JP] |
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7-57472 |
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Current U.S.
Class: |
156/345.27;
118/715; 118/723I; 118/723MA; 118/723E; 118/723MR; 156/345.37 |
Current CPC
Class: |
H01J
37/32504 (20130101); H01J 37/32522 (20130101); H01L
21/6831 (20130101); H01L 21/67069 (20130101); H01L
21/67109 (20130101); H01L 21/3065 (20130101); H01J
2237/022 (20130101) |
Current International
Class: |
H01J
37/32 (20060101); C23C 016/00 () |
Field of
Search: |
;216/67,70 ;156/345
;118/723MR,723MA,723E,723I,715 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 488 307 A2 |
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Jun 1992 |
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EP |
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58-153332 |
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Sep 1983 |
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JP |
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Primary Examiner: Lund; Jeffrie R
Attorney, Agent or Firm: Antonelli, Terry, Stout &
Kraus, LLP
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part application of to U.S.
application Ser. No. 08/611,758, entitled "Plasma Processing
Apparatus and Plasma Processing Method", filed Mar. 8, 1996, by
some of the inventors herein, the subject matter of the
aforementioned application being incorporated by reference herein.
Claims
What is claimed is:
1. A plasma etching apparatus comprising a vacuum processing
chamber, a plasma generation device, a processing gas supply for
supplying processing gas to said processing chamber, an electrode
for holding a sample to be processed in said vacuum processing
chamber, and an evacuation system for reducing the pressure of said
vacuum processing chamber, wherein:
said processing gas includes at least one kind of gas having a
composition for forming a polymerized film by plasma discharge;
said processing gas is made plasmatic by plasma discharge in said
processing chamber; and
at least one surface of an inner wall surface of said processing
chamber in contact with plasma in said processing chamber and a
surface of an internal component part is controlled to a
predetermined temperature which is lower than the temperature of
said sample to be processed and a strong polymerized film is formed
on said inner wall surface of said processing chamber.
2. A plasma etching apparatus according to claim 1, wherein the
temperature of said inner wall surface of said processing chamber
is set to a predetermined temperature which is lower than the
temperature of said sample by 5.degree. C. or more and controlled
with the accuracy of less than .+-.10.degree. C.
3. A plasma etching apparatus according to claim 1, wherein the
temperature of said inner wall surface of said processing chamber
is set to a predetermined temperature which is lower than the
temperature of a sample by 20.degree. C. or more and controlled
with the accuracy of less than .+-.10.degree. C.
4. A plasma etching apparatus according to claim 1, wherein the
temperature of said inner wall surface of said processing chamber
is set to a predetermined temperature within a range from 0.degree.
C. to 100.degree. C. and controlled with the accuracy of less than
.+-.10.degree. C.
5. A plasma etching apparatus according to claim 1, wherein the
temperature of said inner wall surface of said processing chamber
is set to a predetermined temperature within a range from
20.degree. C. to 80.degree. C. and controlled with the accuracy of
less than .+-.10.degree. C.
6. A plasma etching apparatus according to one of claims 1 to 5,
wherein the processing pressure in said processing chamber is set
within a range from 0.1 Pa to 10 Pa.
7. A plasma etching apparatus according to one of claims 1 to 5,
wherein the processing pressure in said processing chamber is set
within a range from 0.5 Pa to 4 Pa.
8. A plasma etching apparatus according to one of claims 1 to 5,
wherein the member constituting said inner wall surface of said
processing chamber has an exchangeable structure.
9. A plasma etching apparatus according to claim 6, wherein the
member constituting said inner wall surface of said processing
chamber has an exchangeable structure.
10. A plasma etching apparatus according to claim 7, wherein the
member constituting said inner wall surface of said processing
chamber has an exchangeable structure.
11. A plasma etching apparatus according to one of claims 1 to 5,
wherein said apparatus includes a process of controlling the growth
of a polymerized film formed on said inner wall surface of said
processing chamber.
12. A plasma etching apparatus according to claim 6, wherein said
apparatus includes a process of controlling the growth of a
polymerized film formed on said inner wall surface of said
processing chamber.
13. A plasma etching apparatus according to claim 7, wherein said
apparatus includes a process of controlling the growth of a
polymerized film formed on said inner wall surface of said
processing chamber.
14. A plasma etching apparatus according to claim 8, wherein said
apparatus includes a process of controlling the growth of a
polymerized film formed on said inner wall surface of said
processing chamber.
15. A plasma etching apparatus comprising a vacuum processing
chamber, a plasma generation device, a processing gas supply for
supplying gas to said processing chamber, an electrode for holding
a sample to be processed in said vacuum processing chamber, and an
evacuation system for reducing the pressure of said vacuum
processing chamber, wherein: at least one of component parts of an
inner wall of said processing chamber in contact with plasma in
said processing chamber is structured so that bias power is applied
to at least one part of a surface of said at least one component
parts, and a heat capacity of said at least one of component parts
is made sufficiently small, and a surface area of said at least one
of component parts in contact with plasma is made smaller.
16. A plasma etching apparatus according to claim 15, wherein a
temperature of said at least one of component parts of said inner
wall is set within a range from 100.degree. C. to 250.degree.
C.
17. A plasma etching apparatus according to claim 15, wherein a
temperature of said at least one of component parts of said inner
wall is set within a range from 150.degree. C. to 200.degree.
C.
18. A plasma etching apparatus according to one of claims 16 and
17, wherein the processing pressure in said processing chamber is
set within a range from 0.1 Pa to 10 Pa.
19. A plasma etching apparatus according to one of claims 16 and
17, wherein the processing pressure in said processing chamber is
set within a range from 0.5 Pa to 4 Pa.
20. A plasma etching apparatus according to one of claims 16 and
17, wherein said at least one of component parts of said inner wall
is ring-shaped and the surface area of said at least one of
component parts in contact with plasma is 20% of the total area of
said inner wall of said processing chamber or less.
21. A plasma etching apparatus according to claim 18, wherein said
at least one of component parts of said inner wall is ring-shaped
and the surface area of said at least one of component parts in
contact with plasma is 20% of the total area of said inner wall of
said processing chamber or less.
22. A plasma etching apparatus according to claim 19, wherein said
at least one of component parts of said inner wall is ring-shaped
and the surface area of said at least one of component parts in
contact with plasma is 20% of the total area of said inner wall of
said processing chamber or less.
23. A plasma etching apparatus according to one of claims 16 and
17, wherein said at least one of component parts of said inner wall
is ring-shaped, and a thickness of said at least one of component
parts is 6 mm or less, and an inner diameter is a diameter of a
sample or more.
24. A plasma etching apparatus according to claim 18, wherein said
at least one of component parts of said inner wall is ring-shaped,
and a thickness of said at least one of component parts is 6 mm or
less, and an inner diameter is a diameter of a sample or more.
25. A plasma etching apparatus according to claim 19, wherein said
at least one of component parts of said inner wall is ring-shaped,
and a thickness of said at least one of component parts is 6 mm or
less, and an inner diameter is a diameter of a sample or more.
26. A plasma etching apparatus according to claim 20, wherein said
at least one of component parts of said inner wall is ring-shaped,
and a thickness of said at least one of component parts is 6 mm or
less, and an inner diameter is a diameter of a sample or more.
27. A plasma etching apparatus according to claim 15, wherein said
plasma etching apparatus is structured so that an infrared absorber
is formed in the neighborhood of a side of said at least one
component parts of said inner wall which is in contact with plasma
and a temperature of said at least one of component parts is
remotely controlled by an infrared radiator.
28. A plasma etching apparatus according to claim 27, wherein a
temperature of said at least one of component parts of said inner
wall is set to a predetermined temperature within a range from
100.degree. C. to 250.degree. C. and adjusted with the accuracy of
less than .+-.10.degree. C.
29. A plasma etching apparatus according to claim 27, wherein a
temperature of said at least one of component parts of said inner
wall is set to a predetermined temperature within a range from
150.degree. C. to 200.degree. C. and adjusted with the accuracy of
less than .+-.10.degree. C.
30. A plasma etching apparatus according to one of claims 1 to 5,
15 to 17 and 27 to 29, wherein said plasma generation device is a
magnetic field UHF band electromagnetic wave radiation and
discharge system, a magnetron system, a parallel plate system, or
an inductive coupling system.
31. A plasma etching apparatus according to claim 6, wherein said
plasma generation device is a magnetic field UHF band
electromagnetic wave radiation and discharge system, a magnetron
system, a parallel plate system, or an inductive coupling
system.
32. A plasma etching apparatus according to claim 7, wherein said
plasma generation device is a magnetic field UHF band
electromagnetic wave radiation and discharge system, a magnetron
system, a parallel plate system, or an inductive coupling
system.
33. A plasma etching apparatus according to claim 8, wherein said
plasma generation device is a magnetic field UHF band
electromagnetic wave radiation and discharge system, a magnetron
system, a parallel plate system, or an inductive coupling
system.
34. A plasma etching apparatus according to claim 9, wherein said
plasma generation device is a magnetic field UHF band
electromagnetic wave radiation and discharge system, a magnetron
system, a parallel plate system, or an inductive coupling
system.
35. A plasma etching apparatus according to claim 10, wherein said
plasma generation device is a magnetic field UHF band
electromagnetic wave radiation and discharge system, a magnetron
system, a parallel plate system, or an inductive coupling
system.
36. A plasma etching apparatus according to claim 11, wherein said
plasma generation device is a magnetic field UHF band
electromagnetic wave radiation and discharge system, a magnetron
system, a parallel plate system, or an inductive coupling
system.
37. A plasma etching apparatus according to claim 12, wherein said
plasma generation device is a magnetic field UHF band
electromagnetic wave radiation and discharge system, a magnetron
system, a parallel plate system, or an inductive coupling
system.
38. A plasma etching apparatus according to claim 13, wherein said
plasma generation device is a magnetic field UHF band
electromagnetic wave radiation and discharge system, a magnetron
system, a parallel plate system, or an inductive coupling
system.
39. A plasma etching apparatus according to claim 14, wherein said
plasma generation device is a magnetic field UHF band
electromagnetic wave radiation and discharge system, a magnetron
system, a parallel plate system, or an inductive coupling
system.
40. A plasma etching apparatus according to claim 18, wherein said
plasma generation device is a magnetic field UHF band
electromagnetic wave radiation and discharge system, a magnetron
system, a parallel plate system, or an inductive coupling
system.
41. A plasma etching apparatus according to claim 19, wherein said
plasma generation device is a magnetic field UHF band
electromagnetic wave radiation and discharge system, a magnetron
system, a parallel plate system, or an inductive coupling
system.
42. A plasma etching apparatus according to claim 20, wherein said
plasma generation device is a magnetic field UHF band
electromagnetic wave radiation and discharge system, a magnetron
system, a parallel plate system, or an inductive coupling
system.
43. A plasma etching apparatus according to claim 21, wherein said
plasma generation device is a magnetic field UHF band
electromagnetic wave radiation and discharge system, a magnetron
system, a parallel plate system, or an inductive coupling
system.
44. A plasma etching apparatus according to claim 22, wherein said
plasma generation device is a magnetic field UHF band
electromagnetic wave radiation and discharge system, a magnetron
system, a parallel plate system, or an inductive coupling
system.
45. A plasma etching apparatus according to claim 23, wherein said
plasma generation device is a magnetic field UHF band
electromagnetic wave radiation and discharge system, a magnetron
system, a parallel plate system, or an inductive coupling
system.
46. A plasma etching apparatus according to claim 24, wherein said
plasma generation device is a magnetic field UHF band
electromagnetic wave radiation and discharge system, a magnetron
system, a parallel plate system, or an inductive coupling
system.
47. A plasma etching apparatus according to claim 25, wherein said
plasma generation device is a magnetic field UHF band
electromagnetic wave radiation and discharge system, a magnetron
system, a parallel plate system, or an inductive coupling
system.
48. A plasma etching apparatus according to claim 26, wherein said
plasma generation device is a magnetic field UHF band
electromagnetic wave radiation and discharge system, a magnetron
system, a parallel plate system, or an inductive coupling system.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a plasma etching apparatus and
etching method and, more particularly, to a plasma etching
apparatus and etching method suitable for forming a fine pattern in
the semiconductor manufacture process.
In the semiconductor manufacture process, the plasma etching
apparatus is widely used in the fine processing processes, for
example, such as film deposition, etching, and ashing. The process
by plasma etching performs the predetermined process by making
processing gas introduced into the vacuum chamber (reactor)
plasmatic by the plasma generation means, performing the fine
processing by making it react on the surface of a semiconductor
wafer, and discharging volatile reaction products.
In this plasma etching process, the temperatures of the inner wall
of the reactor and wafer and the deposition status of reaction
products on the inner wall greatly affect the process. If reaction
products deposited inside the reactor are peeled off, dust may be
caused, resulting in deterioration of the element characteristics
and reduction of the yield.
Therefore, in the plasma etching apparatus, to keep the process
stable and control generation of foreign substances, it is
important to control the temperature in the reactor and deposition
of reaction products on the surface.
For example, in Japanese Patent Application Laid-Open 8-144072, for
the purpose of improving the selection ratio in the dry etching
process of a silicon oxide film, a dry etching apparatus for
controlling and holding the temperature of each unit inside the
reactor at a high temperature within a range of 150.degree. C. to
300.degree. C. (desirably from 200.degree. C. to 250.degree. C.)
which is higher than the temperature at the etching stage of
150.degree. C. or more with the accuracy of less than .+-.5.degree.
C. is described. When the temperature of each unit of the inner
surface of the reactor is increased and controlled at a high value
by heating like this, the deposited amount of plasma polymeric
products on the inner surface of the reactor reduces, and the
deposited amount of plasma polymeric products on a semiconductor
wafer increases, and the selection improves.
In Japanese Patent Application Laid-Open 5-275385, a parallel plate
type plasma etching apparatus in which a heating means for
increasing and keeping the temperature so that reaction products
generated by the plasma etching will not be deposited is installed
on at least one of the clamp ring (workpiece holding means) and
focus ring (plasma centralization means) is described. As a heating
means, a resistance heating element is used. Deposition of reaction
products can be prevented by heating, so that peeling of reaction
products and deposition of particles on the surface of a workpiece
can be reduced.
As mentioned above, in the plasma etching apparatus, it is
important to control the temperature of the surface of the inner
wall of the chamber and deposition of reaction products on the
surface of the inner wall.
However, when the temperature of the inner wall surface of the
chamber, particularly the temperature of the side wall surface
having a wide area is set to a high value between 200.degree. C.
and 250.degree. C. or more, the etching characteristic becomes very
sensitive to the temperature of the inner wall surface and a
problem arises that the reproducibility and reliability of the
process are apt to reduce.
For example, in S. C. McNevin, et al., J. vac. Sci.
Technol. B 15(2) March/April 1997, p. 21, Chemical challenge of
submicron oxide etching, it is indicated that when the side wall
temperature changes from 200.degree. C. to 170.degree. C. in
inductive coupling plasma, the oxide film etching rate increases
more than 5%. As a reason, it is inferred that since the side wall
temperature lowers, much more carbon is adsorbed into the wall, and
deposition of carbon on a wafer reduces, and the oxide film etching
rate increases. As mentioned above, since high density plasma,
particularly, performs a strong interaction with the inner wall of
the reactor in the high temperature zone, deposition of reaction
products on the inner wall surface and composition change of the
surface proceed rapidly due to a change in the temperature balance
inside the reactor and appear as a change in the etching
characteristic.
Furthermore, in the high temperature zone, the aforementioned
interaction between the plasma and the inner wall becomes very
sensitive to a change in temperature. For example, when SiO2 is
used as a material of the inner wall surface, a thermodynamic
relationship between the etching rate by F atoms of SiO2 and the
wall temperature is reported (D. L. Flamm, et al., J. Appl. Phys.,
50, p. 6211 (1979)), and when this relationship is applied to a
temperature zone of more than 150.degree. C., the etching rate
rapidly increases exponentially when the wall temperature is
between 200.degree. C. and 250.degree. C. or more.
Therefore, in such a high temperature zone, the temperature control
requires high accuracy such as .+-.5.degree. C. max. However, the
inner wall surface is exposed to high density plasma, so that it is
not easy to control the wall surface temperature with high accuracy
in such a high temperature zone. To realize it, a temperature
detection means and a heating means such as a heater and lamp are
used for temperature control, though the temperature control
mechanism and means are largely scaled. Furthermore, in such a high
temperature zone, reaction products are not deposited on the inner
wall surface, so that the wall surface is etched and consumed by
plasma. Therefore, it is necessary to periodically exchange the
parts of the inner wall surface and an increase in the cost of
expendable supplies results. Heating requires large energy, thus
the high temperature zone is not desirable also from a viewpoint of
energy consumption.
The same problem is imposed also by heating the ring around a wafer
and the electrode. When the ring is heated to increase the
temperature thereof, deposition of reaction products can be
prevented, though the heating mechanism such as the resistance
heating element makes the equipment constitution complex. When the
ring and inner wall surface are etched and consumed by plasma even
if deposition of reaction products can be prevented, there is the
possibility that the constitution material itself will become a new
dust source. Furthermore, when the parts of the ring and inner wall
surface are consumed, it is necessary to periodically exchange them
and the running cost of the equipment increases.
One method for solving such a problem is to protect the inner wall
surface of the chamber by a surface coating layer of a polymer. For
example, in Japanese Patent Application Laid-Open 7-312363, a
plasma etching apparatus for keeping the temperature of the
workpiece (article to be processed) holder higher than that of the
wall surface of the chamber and forming a surface coating layer on
the inner wall surface of the chamber is described. By catching and
storing contaminant particles in a polymer film, remaining and
storing of contaminants in the chamber due to reaction products can
be reduced.
However, the purpose in this case is not to protect the wall
surface but to catch contaminant particles. It is just described
that the temperature for forming a surface coating layer on the
inner wall surface of the chamber is lower than that of a workpiece
(article to be processed) by more than 5.degree. C. and the
temperature range and control accuracy are not taken into account.
The pressure range is a high pressure range such as several
hundreds mtorr (several tens Pa). However, it is inferred that the
deposition temperature of a film changes the composition and
quality of the film and affects the film peeling strength and
occurrence of foreign substances. It is expected that changing of
the deposited film temperature results in occurrence of cracking
and peeling due to repetition of thermal expansion and shrink and
causes foreign substances and the temperature control accuracy is
an important factor. Within a pressure range of several tens mtorr
max. (several Pa max.), it is considered that the film deposition
condition varies due to high ion energy and a longer mean free
distance of molecules, Furthermore, in the aforementioned prior
art, it is necessary to remove the coating layer catching
contaminants from the wall surface of the plasma etching chamber
and it directly affects the throughput of the equipment and the
cost of expendable supplies. However, this respect is not taken
into account.
SUMMARY OF THE INVENTION
The present invention is designed to eliminate the difficulties
mentioned above and an object of the present invention is to
provide a plasma etching apparatus maintaining the reproducibility
and reliability of the process at a low cost for a long period of
time so as to prevent the etching characteristic from a change with
time by controlling the inner temperature of the reactor and
deposition of reaction products.
The inventors have given diligent study to the aforementioned
problems and as a result of it, found that when the inner wall
surface temperature in the reactor is controlled to a temperature
sufficiently lower than that of a wafer and a constant temperature
within a pressure range of several Pa max. in the reactor, a strong
coating film is formed on the inner wall surface. As a result of
more detailed analysis, the inventors have acknowledged that this
coating film is polymerized much more when the temperature at film
forming time is lower, and when the temperature at film forming
time is controlled constant, a solid layer structure is formed,
accordingly the film surface is not peeled off and damaged and dust
is not caused.
In the above description, that the inner wall surface temperature
in the reactor is "sufficiently lower than that of a wafer and
constant" means that the temperature is controlled with the
accuracy of less than .+-.10.degree. C. within a range lower than
that of a wafer by 5.degree. C. or more, desirably within a range
lower by 20.degree. C. or more. When the temperature of a wafer
during processing is almost within a range from 100.degree. C. to
110.degree. C., it means that the temperature range is 100.degree.
C. or lower, desirably 80.degree. C. or lower.
On the other hand, in the reactor, there is a part or a component
part where the control in the aforementioned low temperature zone
is difficult. The inventors have given study also to such a part
and as a result of it, found a method for controlling the
temperature and deposition of reaction products on the surface
without using a complicated heating mechanism such as a heating
resistor.
The present invention is designed on the basis of the
aforementioned acknowledge and provides a plasma etching apparatus
comprising a vacuum processing chamber, a plasma generation device,
a processing gas supply means for supplying gas to the processing
chamber, an electrode for holding a sample to be processed in this
vacuum processing chamber, and an evacuation system for reducing
the pressure of the vacuum processing chamber, which is
characterized in that the processing gas includes at least one kind
of gas having a composition for forming a polymerized film by
plasma discharge, and the processing gas is made plasmatic by
plasma discharge in the processing chamber, and at least one part
of the inner wall surface (or the surface of an internal component
part) in contact with plasma in the processing chamber is
controlled to a constant temperature which is sufficiently lower
than that of a sample, and a strong polymerized film is formed on
the inner wall surface of the processing chamber.
Another characteristic of the present invention is that the
temperature of the inner wall surface for forming the
aforementioned polymerized film is controlled with the accuracy of
less than +10.degree. C. within a range lower than that of the
sample by 5.degree. C. or more, desirably within a range lower by
20.degree. C. or more.
Another characteristic of the present invention is that the
processing pressure in the processing chamber is set within a range
from 0.1 Pa to 10 Pa, desirably from 0.5 Pa to 4 Pa.
Another characteristic of the present invention is that the member
constituting the inner wall surface of the processing chamber for
forming the aforementioned polymerized film has a structure that it
can be easily exchanged.
Another characteristic of the present invention is that the
apparatus includes a process of controlling the growth of the
aforementioned polymerized film formed on the inner wall surface of
the processing chamber.
Still another characteristic of the present invention is that in
the plasma etching apparatus comprising a vacuum processing
chamber, a plasma generation device, a processing gas supply means
for supplying gas to the processing chamber, an electrode for
holding a sample to be processed in this vacuum processing chamber,
and an evacuation system for reducing the pressure of the vacuum
processing chamber, the component part (or the inner wall surface)
in contact with plasma in the processing chamber is structured so
that the bias power is applied to at least one part of the
component part, and the heat capacity thereof is made sufficiently
small, and the surface area thereof is made smaller.
Another characteristic of the present invention is that the
temperature of the component part in contact with plasma in the
processing chamber is adjusted within a range from 100.degree. C.
to 250.degree. C., desirably from 150.degree. C. to 200.degree. C.
and furthermore, the processing pressure is set within a range from
0.1 Pa to 10 Pa, desirably from 0.5 Pa to 4 Pa.
Another characteristic of the present invention is that the
component part of the inner wall is ring-shaped and the surface
area of the part in contact with plasma is 20% of the total area of
the inner wall of the processing chamber or less.
Another characteristic of the present invention is that the
component part in contact with plasma in the processing chamber, in
which the bias power is applied to at least one part thereof is
ring-shaped, and the thickness thereof is 6 mm or less, and the
inner diameter thereof is more than the diameter of a sample
Still another characteristic of the present invention is that the
plasma etching apparatus is structured so that an infrared absorber
is formed in the neighborhood of the side of the component part of
the inner wall which is in contact with plasma and the temperature
of the part is remotely controlled by the infrared radiation
means.
Another characteristic of the present invention is that the
temperature of the part whose temperature is controlled by the
aforementioned infrared radiation is controlled with the accuracy
of less than .+-.10.degree. C. within a range from 100.degree. C.
to 250.degree. C., desirably from 150.degree. C. to 200.degree.
C.
Still another characteristic of the present invention is that in
the plasma etching apparatus, the plasma generation apparatus is a
magnetic field UHF band electromagnetic wave radiation and
discharge system.
According to the present invention, a part of processing gas is
polymerized by plasma discharge and a surface coating layer is
formed by polymer on the part of the inner wall of the processing
chamber which is in contact with plasma or the surface of the part.
By controlling the temperature of the inner wall surface of the
reactor to a constant temperature sufficiently lower than that of a
wafer, the polymerization of the coating layer proceeds and a solid
layer structure can be formed. Therefore, the inner wall surface
will not be etched and consumed by plasma, so that the frequency of
part exchange of the inner wall surface can be reduced and the
running cost can be decreased. Even if the coating layer is exposed
to plasma, peeling and damage are not caused to the surface thereof
because the film composition is dense, so that dust will not be
caused.
Since the temperature of the inner wall surface is set in a
temperature zone lower than that of a wafer, as compared with a
case that the temperature of the inner wall surface is set in a
high temperature zone of 200.degree. C. or more, the interaction
between plasma and the inner wall surface is weak and not sensitive
to a change in temperature. As a result, the reproducibility and
reliability of the process hardly reduce for a long period of time
and the accuracy of temperature control may be, for example, less
than .+-.10.degree. C. and can be realized comparatively easily
without using a complicated mechanism for temperature control.
When a polymerized film exceeding a predetermined value is formed
on the inner wall surface, it is necessary to remove this film.
When the equipment is exposed to the air, and the component part of
the inner wall surface of the processing chamber on which the
polymerized film is formed is exchanged, and the equipment is
reoperated, and the film is removed by wet cleaning on an ex-situ
basis after removal from the chamber instead of plasma cleaning,
and the inner wall surface is reproduced, satisfactory results can
be produced such that the non-operation time of the equipment is
reduced, and the throughput is prevented from reduction, and the
cost of expendable supplies can be reduced by reproduction and
repetitive use of parts. When a process of controlling the growth
of the polymerized film is added to the process, the time up to
opening and cleaning of the equipment can be prolonged.
On the other hand, according to still another characteristic of the
present invention, with respect to a part or component part for
which the temperature control in a temperature zone sufficiently
lower than that of a wafer is difficult, when a structure that the
bias power is applied to at least one part thereof is installed in
the reactor and the heat capacity of the whole part is made
sufficiently small, the whole part can be controlled in a high
temperature zone without using a complicated mechanism such as a
heater and lamp, so that excessive deposition of reaction products
is controlled and an occurrence of foreign substances caused by
peeling of reaction products can be reduced. When the surface area
of the part is made smaller, the effect on the process can be
controlled even if the temperature and surface condition are
changed. Furthermore, when the magnitude of bias power to be
applied to the component part is adjusted and the temperature is
set within a range from 100.degree. C. to 250.degree. C., desirably
from 150.degree. C. to 200.degree. C., as compared with a case that
the temperature is set within a high temperature zone of about
250.degree. C. or more, the process is not sensitive to a change in
temperature, so that there is an advantage that the temperature
change of the component part can be made smaller to a level that
will not substantially affect the process.
According to still another characteristic of the present invention,
the temperature of the component part in contact with plasma in the
processing chamber can be controlled more actively with high
accuracy in a high temperature zone using infrared radiation and
gas heat transfer, so that excessive deposition of reaction
products is controlled, and an occurrence of foreign substances
caused by peeling of reaction products can be reduced, and the
effect on the process also can be controlled by controlling changes
in the temperature and surface condition. Furthermore, when the
temperature is controlled with the accuracy of less than
.+-.10.degree. C. within a range from 100.degree. C. to 250.degree.
C., desirably from 150.degree. C. to 200.degree. C., as compared
with a case that the temperature is set within a high temperature
zone of about 250.degree. C. or more, the process is not sensitive
to a change in temperature, so that there is an advantage that the
temperature change of the component part can be made smaller to a
level that will not substantially affect even a finer process.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross sectional schematic diagram of a plasma etching
apparatus which is an embodiment of the present invention.
FIG. 2 is a drawing showing the temperature control method of a
sample holder ring which is an embodiment of the present
invention.
FIG. 3 is a drawing showing the temperature control method of a
ring which is an embodiment of the present invention.
FIG. 4 is a drawing showing the temperature control method of a
ring by an infrared lamp which is an embodiment of the present
invention.
FIG. 5 is a drawing showing the temperature control method of a
ring by a refrigerant which is an embodiment of the present
invention.
FIG. 6 is a cross sectional schematic diagram of a magnetic field
RIE plasma etching apparatus which is an embodiment of the present
invention.
FIG. 7 is a cross sectional schematic diagram of a parallel plate
type plasma etching apparatus which is an embodiment of the present
invention.
FIG. 8 is a cross sectional schematic diagram of an inductive
coupling type plasma etching apparatus which is an embodiment of
the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The embodiments of the present invention will be explained
hereunder with reference to the accompanying drawings.
FIG. 1 shows an embodiment that the present invention is applied to
a plasma etching apparatus of a magnetic field UHF band
electromagnetic wave radiation and discharge system and is a cross
sectional schematic diagram of the said plasma etching
apparatus.
In FIG. 1, a processing chamber 100 is a vacuum vessel which can
realize the degree of vacuum of about 10.sup.-6 Torr and the
apparatus has an antenna 110 for radiating electromagnetic waves as
a plasma generation means in an upper part of the processing
chamber and a lower electrode 130 for loading a sample W such as a
wafer in a lower part of the processing chamber. The antenna 110
and the lower electrode 130 are installed opposite to each other in
parallel. A magnetic field forming means 101 comprising
electromagnetic coils 101A and 101B and a yoke 101C is installed
around the processing chamber 100 and a magnetic field having a
predetermined distribution and intensity is formed. By the
interaction of electromagnetic waves radiated from the antenna 110
and the magnetic field formed by the magnetic field forming means
101, processing gas introduced into the processing chamber is made
plasmatic, and plasma P is generated, and the sample W is
processed.
On a side wall 102 of the processing chamber 100, a jacket 103 for
controlling the temperature of the inner surface of the side wall
is held in the exchangeable state. A heat exchanging medium is
circulated and supplied into the jacket 103 from a heat exchanging
medium supply means 104 so as to control the temperature. The
temperature of the jacket is controlled with the accuracy of less
than .+-.10.degree. C. within a range from 0.degree. C. to
100.degree. C., desirably from 20.degree. C. to 80.degree. C. On
the other hand, the processing chamber 100 is evacuated by an
evacuation system 106 connected to a vacuum chamber 105 and the
inside of the processing chamber 100 is adjusted to a predetermined
processing pressure within a range from 0.1 Pa to 10 Pa, desirably
from 0.5 Pa to 4 Pa. The processing chamber 100 and the vacuum
chamber 105 are set at the grounding potential. With respect to the
side wall 102 of the processing chamber 100 and the jacket 103, the
surface treatment such as plasma resistant anodized aluminum may be
carried out on the surface thereof as a thermally conductive
nonmagnetic metallic material including no heavy metal, for
example, such as aluminum.
The antenna 110 radiating electromagnetic waves comprises a disc
electricity conductor 111, a dielectric 112, and a dielectric ring
113 and is held by a housing 114 which is a part of the vacuum
vessel. A plate 115 is installed on the surface of the side of the
disc electricity conductor 111 which is in contact with plasma and
a ring 116 is further installed on the periphery thereof.
Processing gas for performing the processes of etching of samples
and film deposition is supplied from a gas supply means 117 at a
predetermined flow rate and mixture ratio, controlled to a
predetermined distribution via many holes provided in the disc
electricity conductor 111 and the plate 115, and supplied to the
processing chamber 100.
An antenna power source 121 and an antenna high frequency power
source 122 are connected to the disc electricity conductor 111
respectively via filter systems 123 and 124 of the matching circuit
and connected to the ground via a filter 125. The antenna power
source 121 supplies power at a UHF band frequency desirably within
a range from 300 MHz to 900 MHz and electromagnetic waves in the
UHF band are radiated from the antenna 110. On the other hand, the
antenna high frequency power source 122 applies the bias power, for
example, at a low frequency of about 100 kHz or a high frequency
within a range from several MHz to about 10 MHZ to the disc
electricity conductor 111, thus controls the reaction on the
surface of the plate 115 in contact with the disc electricity
conductor 111. Since the plate 115 is opposite to a wafer, it
affects the process most greatly. However, since the bias power is
applied to the surface so as to prevent reaction products from
deposition, the equipment process is stabilized. Furthermore, for
example, when high-purity silicone or carbon is used as a material
of the plate 115 in oxide film etching using CF series gas, the F
radical or CFx radical reaction on the surface of the plate 115 is
controlled and the radical composition ratio is adjusted. The
distance between the under surface of the plate 115 and the wafer W
(hereinafter, it is called the gap) is within a range from 30 mm to
150 mm, desirably from 50 mm to 120 mm.
The disc electricity conductor 111 is kept at a predetermined
temperature by a temperature control means not shown in the
drawing, that is, by a heat exchanging medium circulating through
it and the surface temperature of the plate 115 in contact with the
disc electricity conductor 111 is controlled. The ring 116 is
heated by the bias power from the antenna high frequency power
source 122 and the temperature thereof is controlled. It will be
described later in detail.
At the lower part of the processing chamber 100, the lower
electrode 130 is installed opposite to the antenna 110. A bias
power source 141 for supplying bias power within a range from 400
kHz to 13.56 MHz is connected to the lower electrode 130 via a
filter system 142 of the matching circuit, controls the bias power
to be supplied to the sample W, and is connected to the ground via
a filter 143.
The lower electrode 130 loads and holds the sample W such as a
wafer on the top thereof, that is, on the sample loading surface by
an electrostatic chucking device 131. On the top of the
electrostatic chucking device 131, an electrostatic chucking
dielectric layer (hereinafter, abbreviated to an electrostatic
chucking film) is formed. The electrostatic chucking device 131
applies a DC voltage within a range from several hundreds V to
several kv by an electrostatic chucking DC power source 144 and a
filter 145 so as to generate coulomb force acting between the
sample W and the electrostatic chucking device 131 via the
electrostatic chucking film and adsorbs and holds the sample W on
the lower electrode 130. As an electrostatic chucking film, for
example, an dielectric of aluminum oxide or of a mixture of
aluminum oxide and titanium oxide is used.
Furthermore, the sample W is controlled by a temperature control
means not shown in the drawing so that the surface temperature
thereof is set to a predetermined temperature so as to control the
surface reaction thereof. For that purpose, to the lower electrode
130, an inert gas, for example, He gas which is set at a
predetermined flow rate and pressure is supplied to enhance the
thermal conductivity between the electrostatic chucking device 131
and the sample W. By doing this, the temperature of a wafer is
controlled within a range from 100.degree. C. to 110.degree. C. at
its maximum.
A sample holder ring 132 is installed outside the sample W on the
top of the electrostatic chucking device 131. As a material of the
sample holder ring 132, ceramics such as SiC, carbon, silicone, or
quartz is used. The sample holder ring 132 is insulated from the
electrostatic chucking device 131 by an insulator 133 such as
alumina. Furthermore, by leaking and adding a part of the bias
power from the bias power source 141 to the sample holder ring 132
via the insulator 133, it is possible to adjust the application of
the bias power to the sample holder ring 132 and control the
reaction on the surface thereof. For example, when high-purity
silicone is used as a material of the sample holder ring 132 in
oxide film etching using CF series gas, the F radical or CFx
radical reaction on the surface of the sample holder ring 132 is
adjusted by the scavenging action of silicone and particularly the
uniformity of etching on the periphery of a wafer can be improved.
The sample holder ring 132 is heated by the bias power and cooled
by heat transfer gas, thus the temperature thereof is controlled.
It will be described later in detail.
The plasma etching apparatus in this embodiment is structured as
mentioned above and a concrete process, for example, when a silicon
oxide film is to be etched using this plasma etching apparatus will
be explained hereunder by referring to FIG. 1.
Firstly, the wafer W which is an object to be processed is
transferred from a sample transfer mechanism not shown in the
drawing into the processing chamber and loaded and chucked on the
lower electrode 130. The height of the lower electrode is adjusted
as required so as to be set to a predetermined gap. Next, the
inside of the processing chamber 100 is evacuated by the evacuation
system 106. On the other hand, gases necessary to the etching
process of the sample W, for example, C4F8 and Ar are supplied to
the processing chamber 100 from the plate 115 of the antenna 110 by
the gas supply means 117 at a predetermined flow rate and mixture
ratio, for example, at an Ar flow rate of 300 sccm and a C4F8 flow
rate of 9 sccm. At the same time, the processing chamber 100 is
evacuated by the evacuation system 106 and the inside of the
processing chamber 100 is adjusted to a predetermined processing
pressure, for example, 1 Pa. On the other hand, a magnetic field of
a predetermined distribution and intensity is formed by the
magnetic field forming means 101. Electromagnetic waves in the UHF
band are radiated from the antenna 110 by the antenna power source
121 and plasma P is generated in the processing chamber 100 by the
interaction with the magnetic field. The apparatus dissociates
processing gas by this plasma P so as to generate radical ions and
further performs the process such as etching to the wafer W by
controlling the antenna high frequency power source 122 and the
bias power source 141. When the etching process is finished, the
apparatus stops the supply of the power and processing gas and
terminates the etching.
The plasma etching apparatus in this embodiment is structured as
mentioned above and each unit in the reactor, particularly the
inner surface of the side wall 103 and the ring 116, and
temperature control of the sample holder ring 132 and deposition
control of reaction products will be explained in detail
hereunder.
Firstly, the side wall 103 will be explained by referring to FIG.
1. As already explained, the jacket 103 is held inside the side
wall 102 of the processing chamber 100 and the temperature can be
controlled by a heat exchanging medium.
The inventors have experimented with an object of oxide film
etching at a pressure of 2 Pa using a mixed gas series of C4F8 and
Ar as a processing gas and as a result of it, we have found that
when the inner wall surface temperature in the reactor is
controlled to a constant temperature which is sufficiently lower
than the temperature (about 100.degree. C.) of a wafer with the
accuracy of less than .+-.10.degree. C. within a range from
25.degree. C. to 80.degree. C., a strong coating film is formed on
the inner wall surface. Within a pressure range of several tens
mtorr max. (several Pa max.) like this, ions of high energy
increase, so that it can be considered that the ion assist effect
in film deposition is increased and a tight film is formed. The
condition of a deposited film is such that when the side wall
temperature is low, a fine and strong film is formed and when the
side wall temperature is high, a slightly rough film is formed. To
make this change of film characteristic quantitatively clear, the
composition (element density ratio) of a film deposited at a side
wall temperature of each of 25.degree. C., 50.degree. C., and
80.degree. C. has been analyzed by the XPS (X-ray photoelectron
spectroscopy) and the following results have been obtained.
Side wall temperature C(%) F(96) CF ratio 25.degree. C. 45.6 51.1
0.89 50.degree. C. 43.9 53.8 0.82 80.degree. C. 40.6 58.2 0.70
The results show that as the side wall temperature lowers, the film
characteristic becomes richer with carbon. Although not shown
above, the analysis of the C1s peak shows that as the side wall
temperature lowers, the bonding of carbon proceeds and the
polymerization also proceeds. It is inferred that this is
macroscopically observed as a fine and strong film.
During this experiment, the temperature of the side wall surface is
controlled with the accuracy of less than .+-.10.degree. C., so
that it is forecasted that internal stress caused by a temperature
change is not generated during deposition of a film and the film
structure becomes fine. It is confirmed that a solid layer
structure is formed. This film is very fine and strong and even
when a film is deposited tentatively up to a thickness of about 200
microns in the deposition acceleration test, peeling of the film in
the tape peeling test or in the friction test are not observed.
Furthermore, this film is highly resistant to plasma and it is
acknowledged that peeling and damage of the film surface are not
observed even by the processing of plasma and no dust is
caused.
When the temperature of the inner wall surface of the reactor is
controlled to a constant temperature which is sufficiently lower
than the temperature of a wafer as mentioned above, a strong
deposited film free of occurrence of internal thermal stress can be
formed on the inner wall surface of the reactor. This film is
highly resistant to plasma and peeling of reaction products and
adhesion of particles onto the sample surface are reduced, so that
it acts as a protection film for the inner wall of the reactor.
Therefore, the side wall is free of consumption and damage, so that
the exchange frequency of parts of the side wall can be reduced and
the reduction of running cost results. Furthermore, since the side
wall is protected by the deposited film, there is no need to use
ceramics such as SiC which is highly resistant to plasma and the
cost of parts can be reduced. If the side wall temperature is
particularly controlled within a range from normal temperature to
about 50.degree. C., the energy for heating the side wall can be
reduced, so that it is effective in energy conservation. As a
material of the side wall, a thermally conductive metal including
no heavy metals, for example, aluminum may be used.
Since aluminum is exposed in the initial state free of a deposited
film, there is the possibility that the surface will be damaged and
deteriorated by plasma. To prevent it, the surface may be coated
with a highly polymerized material. Or it is also possible, for
example, to anodize the aluminum surface and then fill fine holes
made by the anodizing process with a highly polymerized material.
Needless to say, the hole filling process can be applied to other
than the aluminum anodizing process. When a polymer film exists on
the interface between the aluminum surface and the deposited film
like this, an effect is produced that the adherence of the aluminum
surface and the deposited film is increased and the deposited film
is hardly peeled off. A film may be excessively deposited depending
on the process. If this occurs, it is possible to execute plasma
cleaning in a short time after the wafer processing so as to
control film deposition and keep the film thickness constant.
Next, the sample holder ring will be explained. As already
explained in the embodiment shown in FIG. 1, the sample holder ring
132 controls the reaction on the surface thereof by application of
the bias power, thus can make the etching characteristic
particularly on the periphery of a wafer uniform. Although the
sample holder ring 132 is heated by the bias power in this case, it
is necessary to control the applied bias power and temperature so
as to control the reaction and deposition of a film on the surface
thereof. Moreover, it is desirable to be capable of controlling the
applied bias power and temperature without incorporating a
complicated mechanism into the lower electrode incorporated in the
electrostatic chucking device 131. This can be realized by control
of the leakage bias power and the balance between heating by the
bias power and cooling by heat transfer gas. This embodiment will
be explained by referring to the cross sectional view (half on the
right) of the lower electrode 130 shown in FIG. 2.
The lower electrode 130 holds the sample W by the electrostatic
chucking device 131. The electrostatic chucking device 131 is
insulated from the ground 135 by the insulator 134. In this
embodiment, the sample holder ring 132 is installed opposite to the
electrostatic chucking device 131 via the insulator 133, thus
structured so that a part of the bias power supplied from the bias
power source 141 is leaked and added. The bias power to be applied
can be adjusted by the thickness and material of the insulator 133.
By use of such a bias power application structure, there is no need
to install a wiring structure to the sample holder ring 132 inside
the lower electrode 130 and connect another bias power source to
the sample holder ring 132.
The electrostatic chucking device 131 is kept at a predetermined
temperature by circulation of a temperature control heat medium
(not shown in the drawing). Between the sample W and the surface of
the electrostatic chucking device 131, a flow path 136 of heat
transfer gas (for example, He gas, etc.) is formed and the heat
conduction is kept satisfactory by introduction of heat transfer
gas. In this embodiment, flow 136A and 136B of heat transfer gas
are also formed between the sample holder ring 132, the insulator
133, and the electrostatic chucking device 131. A part of heat
transfer gas for wafer cooling is introduced and the heat
conduction at the contact is kept satisfactory. As a result, the
heat conduction between the sample holder ring 132 and the
electrostatic chucking device 131 kept at a predetermined
temperature is kept satisfactory and the temperature of the sample
holder ring 132 is kept stable. As a result, the temperature change
due to application of the bias power to the sample holder ring 132
is controlled and the surface reaction and sample processing
characteristic in the sample holder ring 132 can be stabilized. At
the same time, deposition of reaction products can be prevented by
heating by the bias power and ion assist, so that peeling of
reaction products and adhesion of particles onto the sample surface
are reduced.
As mentioned above, in the sample holder ring, the surface reaction
and temperature and deposition of a film can be controlled by a
simple structure by application of the leakage bias power and the
balance between heating by the bias power and cooling by heat
transfer gas and long term stabilization of the process and
reduction of foreign substances can be realized.
In this embodiment, the heat conduction is assured by heat transfer
gas. However, another heat conduction means, for example, such as a
thermally conductive sheet may be used.
Next, the antenna 110 will be explained. As already described in
the embodiment shown in FIG. 1, the antenna high frequency power
source 122 is connected to the disc electricity conductor 111 and
the bias power at about 100 kHz or within a range from several MHz
to about 10 MHz is applied. The temperature of the disc electricity
conductor 111 is kept at a predetermined value by a heat exchanging
medium. Therefore, the plate 115 in contact with the disc
electricity conductor 111 is applied with the bias power and the
surface temperature thereof is also controlled. Since the plate 115
is opposite to a wafer, it affects the process most greatly.
However, when the bias power is applied to this surface so as to
prevent reaction products from deposition and further the surface
reaction by the scavenging action is used using high-purity
silicone as a material of the plate, the process can be
stabilized.
On the other hand, the ring 116 on the periphery of the plate 115
is heated by the bias power by the antenna high frequency power
source 122 in the same way as with the plate 115 and moreover the
heat capacity of the ring 116 is made smaller, thus the
responsibility to temperature change is enhanced. This will be
explained by referring to FIG. 3.
FIG. 3 shows an embodiment showing the temperature control method
for the ring 116. In this embodiment, the ring 116 is structured so
that the shape thereof is made thinner, and a part thereof covers
the plate 115, and the thermal contact with the dielectric ring 113
and the plate 115 is minimized. When the antenna high frequency
power is applied to the plate 115 in this case, ions are pulled
into the surface of the ring 116 in the direction of the arrow
shown in the drawing by the bias power to the plate 115. A heating
mechanism such a heater and lamp is not used in this embodiment, so
that there is an advantage that the mechanism will not be
complicated.
The width w of the part of the ring 116 to which the bias power is
applied is set to, for example, 10 mm or more so that the part can
be efficiently heated by the bias power. The thickness of the ring
116 is set to, for example, 6 mm or less, desirably 4 mm or less so
as to be validly heated by the bias power. When the shape is made
thinner like this, the heat capacity of the ring 115 is made
smaller. As a result, the whole ring can be heated almost within a
range from 100.degree. C. to 250.degree. C., desirably from
150.degree. C. to 200.degree. C. As a result, the deposition of
reaction products is controlled and the occurrence of foreign
substances due to peeling of reaction products can be reduced.
Within this temperature range, the change in surface reaction is
not sensitive to the change in temperature compared with that in a
high temperature zone of about 250.degree. C. or more, so that
there is an advantage that the temperature change in component
parts can be made smaller to such a level that will not
substantially affect the process.
The thickness of the ring 116 can be decided by the antenna bias
power frequency, the material of the ring 116, and the balance of
the deposition speed of reaction products to the ring 116 so as to
control the film deposition and prevent the ring surface from
sputtering and consuming by ions. As shown in the drawing, it is
possible to make the parts other than the part to be applied with
the bias power thinner and make the heat capacity of the whole ring
smaller. When the heat capacity of the ring 116 is made smaller
like this, the responsibility is satisfactory in a short time at
the initial stage of the process and the temperature rises, so that
the effect on the processing characteristic is small. It is
desirable that the inner diameter d of the ring 116 is larger than
the diameter of a sample. Since the inner diameter of the reactor
is about 1.5 times of the diameter of a sample, when the diameter
of a sample is 300 mm, the width s of the ring is almost within a
range from 50 mm to 70 mm and the surface area thereof is
sufficiently small for the whole inner wall surface of the reactor,
for example, such as 20% or less. When the surface area of parts is
made smaller like this, even if the temperature and surface
condition are changed, the effect on the process can be controlled.
Moreover, since the ring 116 is positioned on the periphery
compared with a wafer, the effect on the process is made more
smaller.
In the aforementioned embodiment, since passive heating by plasma
is used, a certain degree of temperature change is unavoidable.
This change may affect the etching characteristic due to fine
division of the process though the effect is not actualized in the
current process and if this occurs, a positive temperature control
mechanism by a lamp and heater is required. FIG. 4 shows an
embodiment of a temperature control mechanism by heating of a
lamp.
In this embodiment, the dielectric ring 113A is structured so that
a part thereof can apply the bias power by the same structure 116A
as that of the ring 116 and furthermore, on the side of the
dielectric ring 113A close to plasma, an infrared absorber 151 for
absorbing infrared light and far infrared light, for example, an
aluminum thin film is formed. Infrared light and far infrared light
are radiated from an infrared radiation means 152, pass through an
infrared transmission window 153 and the dielectric ring 113A, are
absorbed by the infrared absorber 151, and heat the ring 116. The
infrared absorber 151 can be remotely heated by infrared light, so
that when the infrared absorber 151 is installed on the side of the
dielectric ring 113A close to plasma, the temperature of the
surface of the dielectric ring 123 exposed to plasma can be
controlled with higher accuracy. The heating mechanism uses
absorption of infrared light, so that there is an advantage that
the responsibility is better compared with heating by a heating
resistor. Furthermore, the dielectric ring 113A is heated also by
the bias power by the bias power application unit 116A, so that the
responsibility to temperature is improved.
On the other hand, the infrared radiation means 152 is installed in
a holder 154. A gap is provided between the holder 154 and the
dielectric ring 113A and heat transfer gas for temperature control
is supplied to the gap via a gas supply means 155. Heat transfer
gas is sealed by vacuum sealing means 156A and 156B. The dielectric
ring 113A radiates heat by this gas heat transfer via the holder
154. Therefore, for example, by heating by the bias power and lamp
at start of the process and radiating heat by gas heat transfer
during the process, the accuracy of temperature control is
improved. As a result, the temperature of the dielectric ring 123
can be controlled with the accuracy of about .+-.5 to 10.degree. C.
almost within a range from 100.degree. C. to 250.degree. C.,
desirably from 150.degree. C. to 200.degree. C. The film deposition
is reduced at this temperature, so that the occurrence of foreign
substances due to peeling of a film is controlled. The surface
condition of the dielectric ring 113A is in the region greatly
dependent on the temperature, so that the surface condition is not
changed and a plasma process which is stable over a long period is
realized.
In the embodiments shown in FIGS. 3 and 4, the film deposition is
reduced by heating the ring 116 in contact with plasma and the
dielectric ring 113A. However, the ring in contact with plasma is
controlled to a constant temperature which is lower than the
temperature of a wafer in the same way as with the inner surface of
the side wall explained in FIG. 1 and a stable deposited film can
be formed. FIG. 5 shows this embodiment and the dielectric ring
113B is controlled almost within a range from 20.degree. C. to
100.degree. C. under temperature control by a refrigerant.
In this embodiment, a refrigerant for temperature control is
supplied to a refrigerant flow path 161 installed in the dielectric
ring 113B from a heat exchanging medium supply means 162. The
refrigerant is sealed by a sealing means 163. The temperature of
the dielectric ring 113B is kept at a predetermined value by a
temperature controller and temperature detector which are not shown
in the drawing. By use of this constitution, the temperature of the
dielectric ring 113B can be kept almost within a range from
20.degree. C. to 100.degree. C. during plasma processing.
Therefore, a stable and strong film of reaction products is
deposited on the surface of the dielectric ring 123, so that the
surface of the dielectric ring 123 will not be etched and consumed.
When a film is excessively deposited depending on the process, the
film may be kept at a constant thickness by concurrently using
plasma cleaning.
Each of the aforementioned embodiments uses a plasma etching
apparatus of a magnetic field UHF band electromagnetic wave
radiation and discharge system. However, electromagnetic waves to
be radiated may be, for example, microwaves at 2.45 GHz or waves in
the VHF band almost within a range from several tens MHz to 300 MHz
in addition to the UHF band. The magnetic field is not always
necessary and, discharge of nonmagnetic field microwaves, for
example, is acceptable.
Furthermore, in addition to the above, the aforementioned
embodiments can be applied to, for example, a magnetron type plasma
etching apparatus using the magnetic field, a plasma etching
apparatus of a parallel plate type capacitively coupled system, or
an inductive coupling type plasma etching apparatus.
FIG. 6 shows an example that the present invention is applied to an
RIE apparatus (a magnetron RIE apparatus or magnetically enhanced
RIE apparatus). The processing chamber 100 as a vacuum vessel has
the side wall 102, the lower electrode 130 for loading the sample W
such as a wafer, and an upper electrode 201 to be grounded opposite
to it and also has the gas supply means 117 for introducing
predetermined gas into the vacuum vessel, the evacuation system 106
for decompressing and evacuating the vacuum vessel, an electric
field generation means 203 for generating an electric field between
the lower electrode and the upper electrode, and a magnetic field
generation means 202 for generating a magnetic field inside the
vacuum vessel. The magnetic field generation means 202 has a
plurality of permanent magnets or coils which are arranged in a
ring-shape on the periphery of the processing chamber 100 and forms
a magnetic field almost parallel to the electrodes inside the
processing chamber. The magnetic field generation means 202 makes
processing gas plasmatic by the electric field generated between
the electrodes, generates plasma P, and processes the sample W.
Furthermore, in the magnetron RIE, a magnetic field is formed
almost perpendicularly to the electric field by the magnetic field
generation means 202, so that the collision frequency between
electrons and molecules and atoms in plasma increases, and the
plasma density increases, and a high etching characteristic is
obtained.
In this embodiment, in the same way as with the embodiment
described in FIG. 1, the jacket 103 for controlling the temperature
of the inner surface of the side wall is held by the side wall 102
in the exchangeable state, and a heat exchanging medium is
circulated and supplied into the jacket 103 from the heat
exchanging medium supply means 104, and the temperature of the
jacket is controlled with the accuracy of less than .+-.10.degree.
C. within a range from 0.degree. C. to about 100.degree. C.,
desirably 20.degree. C. to about 80.degree. C. The jacket 103
comprises, for example, anodized aluminum.
By use of this constitution, the inner wall surface of the reactor
can be controlled to a constant temperature which is sufficiently
lower than the temperature of a wafer, so that a strong deposited
film can be formed on the inner surface of the side wall of the
reactor. This film is highly resistant to plasma and acts as a
protection film for the inner wall of the reactor and peeling of
reaction products and adhesion of particles onto the sample surface
are reduced. Therefore, the side wall is free of consumption and
damage, so that the exchange frequency of parts of the side wall
can be reduced, and the reduction of running cost results, and
there is no need to use ceramics such as SiC which is highly
resistant to plasma, and the cost of parts can be reduced.
In this embodiment, in the same way as with the embodiment
described in FIGS. 1 and 2, it is structured so that a part of the
bias power supplied from the electric field generation means 203 is
leaked to the sample holder ring 132 and furthermore, by cooling by
gas heat transfer, the surface reaction and sample processing
characteristic in the sample holder ring 132 can be stabilized. At
the same time, deposition of reaction products can be prevented by
heating by the bias power and ion assist, so that peeling of
reaction products and adhesion of particles onto the sample surface
are reduced.
FIG. 7 shows an example that the present invention is applied to a
parallel plate type plasma etching apparatus. The processing
chamber 100 as a vacuum vessel has the side wall 102, the lower
electrode 130 for loading the sample W such as a wafer, an upper
electrode 210 opposite to it, and an electric field generation
means 221 for supplying power to the upper electrode 210 and
generating an electric field between the electrodes. Predetermined
processing gas is supplied into the processing chamber 100 by the
gas supply means 117 and the vacuum vessel is decompressed and
evacuated by the vacuum system 106. Processing gas is made
plasmatic by the electric field generated between the electrodes,
and plasma P is generated, and the sample W is processed. The upper
electrode 210 is held by a housing 214 with an electrode plate 211
insulated by insulators 212 and 213. A plate 215 is installed on
the side of the electrode plate 211 in contact with plasma and a
shield ring 216 is installed on the periphery thereof. The shield
ring 216 protects the insulators 212 and 213 from plasma,
simultaneously increases the plasma density by sealing the plasma P
in the processing chamber 100 in the state that it is positioned
opposite to the sample holder ring 132, and obtains a high etching
characteristic.
In this embodiment, in the same way as with the embodiment
described in FIG. 1, the temperature of the inner surface of the
side wall 102 is controlled by the jacket 103 with the accuracy of
less than .+-.10.degree. C. within a range from 0.degree. C. to
about 100.degree. C., desirably 20.degree. C. to about 80.degree.
C., so that a deposited film resistant to plasma is formed and acts
as a protection film for the inner wall of the reactor, and
particles can be reduced, and the exchange frequency of parts of
the side wall can be reduced. Also with respect to the sample
holder ring 132, the surface reaction and sample processing
characteristic can be stabilized by the leakage bias power
application structure and gas cooling, and the deposition of
reaction products is prevented, and the occurrence of particles is
reduced. Furthermore, in the same way as with the embodiment shown
in FIG. 3, the shield ring 216 is structured so that the shape
thereof is thin, and a part of the shield ring 216 covers the plate
115, and the thermal contact with other parts is minimized. As a
result, when power is applied to the plate 115, the shield ring 216
is heated by ions due to the self bias power, and the deposition of
reaction products is controlled, and the occurrence of foreign
substances is reduced.
FIG. 8 shows an example that the present invention is applied to an
inductively coupled type plasma etching apparatus. The processing
chamber 100 as a vacuum vessel has the side wall 102, the lower
electrode 130 for loading the sample W such as a wafer, and a top
plate 230 and is decompressed and evacuated by the vacuum system
106. On the top of the top plate 230, inductive discharge coils 231
are arranged and high frequency power is supplied from a high
frequency power source 232. Processing gas is supplied from the gas
supply means 117 and made plasmatic by inductive discharge by the
inductive discharge coils 231, and plasma P is generated, and the
sample W is processed. In the inductive coupling type plasma
etching apparatus, silicone is used as a material of the top elate
so as to stabilize the process and the interaction between plasma
and the wall is controlled by a means, for example, a Faraday
shield or a magnetic field, thus even if the temperature of the
side wall is made lower than the temperature of a wafer, a high
etching characteristic can be obtained stably.
In this embodiment, in the same way as with the embodiment
described in FIG. 1, the temperature of the inner surface of the
side wall 102 is controlled by the jacket 103 with the accuracy of
less than .+-.10.degree. C. within a range from 0.degree. C. to
about 100.degree. C., desirably 20.degree. C. to about 80.degree.
C. As a result, a deposited film resistant to plasma is formed and
acts as a protection film for the inner wall of the reactor, and
particles can be reduced, and the exchange frequency of parts of
the side wall can be reduced. Also with respect to the sample
holder ring 132, the surface reaction and sample processing
characteristic can be stabilized by the leakage bias power
application structure and gas cooling, and the deposition of
reaction products is prevented, and the occurrence of particles is
reduced.
In the aforementioned embodiments, the processing object is
semiconductor wafers and the etching process for them is described.
However, the present invention is not limited to it and for
example, it can be applied also to a case that the processing
object is a liquid crystal board and the process itself is not
limited to etching but the present invention can be applied also
to, for example, the sputtering or CVD process.
According to the present invention, a plasma etching apparatus
maintaining the reproducibility and reliability of the process at a
low cost for a long period of time so as to prevent the etching
characteristic from a change with time by controlling the inner
temperature of the reactor and the wall surface condition can be
provided.
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